Teething takes a long time overall - the first teeth start to come through at around 5 or 7 months, but the whole process is likely to take well over a year. It is uncomfortable and can be quite painful, but there are some things you can do to help.
An old and still popular remedy is a teething ring. Chewing on this can be soothing and is a distraction from any pain. The rings work even better if they are chilled for a while in the fridge first, as this helps reduce the uncomfortably hot sensations in the gums. Be careful never to chill them for longer than the instructions say, though. Generally if your baby seems to want to chew on somethng - they will even chew their own fingers to relieve the discomfort - you can also give them a bit of bread or vegetable, eg carrot, to chew on under your supervision.
You can also buy teething gels from the pharmacy, which can give some relief. Medicines such as painkillers should only be given after consulting a pharmacist or health professional.